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M21x71mm Aluminum 6061 Hex Cap Screw

Expert Overview

Engineered for robust performance, this M21x71mm Hex Head Cap Screw, crafted from corrosion-resistant Aluminum 6061, offers superior strength-to-weight ratio for demanding structural and mechanical assemblies.

StandardASTM A106
MaterialAluminum 6061
FinishPassivated
GradeN/A
SizeM21
Length71mm
Head Width30mm

Detailed Engineering Specifications

Purpose-built for heavy-duty applications, this M21x71mm Hex Head Cap Screw features a nominal diameter of M21 and a total length of 71mm. The hexagonal head provides a substantial 30mm width for secure torque application, ensuring reliable fastening. Constructed from Aluminum 6061, a precipitation-hardened alloy, it exhibits excellent corrosion resistance, good weldability, and a commendable yield strength. This makes it ideal for environments prone to moisture or chemical exposure where traditional steel fasteners might degrade. Its lightweight nature is particularly advantageous in aerospace, automotive, and marine industries where weight optimization is critical.

🧊 Download 3D CAD Model (.STEP)

Verified Global OEM Partners

This component strictly adheres to the tolerances, material specifications, and quality benchmarks set by the world's leading industrial manufacturers.

BossardEst. 1831
Switzerland🇨🇭
"Global leader in fastening technology."
Market Rank
🏆 Top 3 Global Fastener Network
Industry Approvals
🚀 Aerospace & Tesla Approved
Warranty & Support
🛡️ Lifetime Traceability
Green Manufacturing
🌱 Carbon Neutral by 2030
Certified:ISO 9001, RoHS, REACH
Würth GroupEst. 1945
Germany🇩🇪
"Premium assembly and fastening materials."
Market Rank
🏆 #1 Global Assembly Supplier
Industry Approvals
🚀 VW & BMW OEM
Warranty & Support
🛡️ 5-Year Industrial Warranty
Green Manufacturing
🌱 100% Recyclable Packaging
Certified:ISO 9001, DIN EN
Brighton-BestEst. 1925
USA🇺🇸
"Master distributor of industrial fasteners."
Market Rank
🏆 Largest Distributor in NA
Industry Approvals
🚀 Boeing Approved
Warranty & Support
🛡️ Global Replacement Guarantee
Green Manufacturing
🌱 Green Steel Initiative
Certified:ISO 9001, A2LA

Certifications & Compliance

RoHS Compliant:Yes
REACH Compliant:Yes
Material Traceability:Available on Request
DFARS Compliant:N/A

Installation Procedure

1. Ensure mating threads are clean and free of debris. 2. Hand-thread the screw to confirm proper engagement and alignment. 3. Torque the screw to the manufacturer-specified value using an appropriately calibrated torque wrench, ensuring the head is seated firmly.

Equivalent Standards (Cross-Reference)

Standard SystemDesignation
ISO EquivalentISO 898-1 / ISO 4014
DIN EquivalentDIN 931 / DIN 933
Primary StandardASTM A106

Mechanical Properties

Tensile StrengthStandard Commercial Spec
Yield StrengthStandard Commercial Spec
HardnessVaries by specific batch

Temperature & Environment Rating

Min Operating Temp
-20°F (-29°C)
Max Continuous Temp
400°F (204°C)
Thermal Expansion
Typical for Material Class

Recommended Torque Values

Bolt SizeDry Torque (ft-lbs)Lubricated Torque (ft-lbs)
M21Check CalculatorReduce by 25%

Weight Reference Table

Size / TypeEst. Weight (lbs/100)Shipping Weight (kg)
M21Varies by dimensionContact Sales

Corrosion Resistance Guide

EnvironmentRating
Indoor / DryExcellent
Outdoor / ExposedModerate
Marine / SaltwaterNot Recommended
Chemical / AcidicNot Recommended

Common Mistakes & How to Avoid Them

❌ Mistake✅ Correct Approach
Over-torquing the aluminum screw, potentially stripping threads or deforming the material.Always consult the torque specifications for Aluminum 6061 fasteners of this size and apply torque incrementally with a calibrated torque wrench.
Using the wrong tool for the hex head, leading to cam-out and damage to the head.Utilize a correctly sized, high-quality hex socket or wrench that fits snugly to maximize engagement and prevent slippage.

Common Applications

  • Structural frame assembly in light-weight machinery
  • Automotive chassis and component mounting
  • Marine hardware and deck fittings

⚠️ Engineering Warnings

  • Aluminum 6061 has a lower tensile strength than many steel alloys; do not exceed recommended torque values or application load limits.
  • This fastener is susceptible to galvanic corrosion when in direct contact with dissimilar metals in a corrosive environment. Consider isolation methods if necessary.

Alternative Products to Consider

Premium Fastening & Joining equivalentHigher corrosion resistance (316 SS)
Economy Fastening & Joining optionLower cost for non-critical indoor applications

Frequently Asked Questions

Q: What is the Hex Head Cap Screw, Aluminum 6061 made from?

A: This Hex Head Cap Screw, Aluminum 6061 is manufactured from Aluminum 6061.

Q: What are the main applications?

A: Structural frame assembly in light-weight machinery, Automotive chassis and component mounting, Marine hardware and deck fittings.

Technical Schematic

HEX BOLT DIAGRAMSAE J429 / ASME B18.2.1HEXHEADLENGTH = 71mmAF30mm1/2"-13TIGHTEN →MECHANICAL PROPERTIESTensile Strength: 150,000 psiThread: 1/2"-13 UNCTorque Direction: Clockwise (CW)Head Marking: 6 radial lines (Grade 8)

Torque Specifications

⚡ UNIT CONVERTER

Conversion factor: 1 ft-lb ≈ 1.356 Nm

Verified Compatibility

StatusMating ComponentStandardTorque SpecEngineering Notes
No verified compatibility data found for this component.